A. Technical Field
The present invention relates to a water-soluble monomer, having a carbon-carbon unsaturated double bond and a carboxyl group, and a production process therefor, and also relates to a water-soluble polymer, a production process therefor, and a composition containing the polymer. This composition is, for example, a detergent composition, an inorganic-pigment dispersant, a fiber-treating agent, a water-treating agent, or a wood pulp-bleaching assistant.
B. Background Art
Hitherto, various organic chelating agents are, for example, used for detergent compositions, dispersants, flocculants, scale inhibitors, chelating reagents, fiber-treating agents, wood pulp-bleaching assistants, pH adjustors, and washing agents.
The organic chelating agents are exemplified by ethylenediaminetetraacetate; nitrilotriacetate; and carboxylic acid-based polymers, such as, homo- or co-polymers of maleic or acrylic acid. Ethylenediaminetetraacetate and nitrilotriacetate are known to have relatively high ability to effectively scavenge heavy-metal ions. In addition, the carboxylic acid-based polymers are known to display excellent chelating and dispersing actions upon inorganic particles, and therefore used over wide scope.
On the other hand, Japanese Unexamined Patent Publication (Kokai) No. S56-61471, U.S. Pat. Nos. 4,172,934 and 4,157,418 disclose monomers which are obtained by introducing one or more carboxyl groups into a carbon atom, which is a constituent of an unsaturated double bond, through an amide bond and an alkylene or phenylene group. Any of these monomers is an amide compound which is obtained by reacting acryloyl or methacryloyl chloride with an amino acid.
However, in terms of per unit weight, ethylenediaminetetraacetate and nitrilotriacetate cannot scavenge a large amount of metal and are also entirely insufficient in inorganic-particle dispersibility which is demanded in various utilization fields.
The aforementioned carboxylic acid-based polymers have structures in which carboxyl groups are directly bonded to carbon atoms of principal chains of the polymers. Therefore, free rotation of the carboxyl groups is hindered and the metal ion scavengeability is insufficient.
In addition, the preceding amide compound can form a polymer having a carboxyl group at a distant site from its principal chain. This polymer, however, has a problem in that its metal ion scavengeability is low, because the density of the carboxylic acid which is present near the principal chain of the polymer (the density of the carboxyl group which is bonded to the principal chain of the polymer directly or through a methylene group) is remarkably low.
Accordingly, chelating agents useful in various utilization fields, namely, compounds which have water solubility, excellent inorganic-particle dispersibility and high scavengeability to heavy metals and can scavenge a large amount of metal ions per unit weight of the compounds, are desired.